ISO 1996-1:2016

INTERNATIONAL ISO
STANDARD 1996-1
Third edition
2016-03-01
Acoustics — Description,
measurement and assessment of
environmental noise —
Part 1:
Basic quantities and assessment
procedures
Acoustique — Description, mesurage et évaluation du bruit de
l’environnement —
Partie 1: Grandeurs fondamentales et méthodes d’évaluation
Reference number
ISO 1996-1:2016(E)
©
ISO 2016

---------------------- Page: 1 ----------------------
ISO 1996-1:2016(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

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ISO 1996-1:2016(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Expression of levels . 2
3.2 Time intervals . 3
3.3 Ratings . 4
3.4 Sound designations . 4
3.5 Impulsive sound sources . 6
3.6 Day, evening, night sound levels . 6
4 Symbols . 7
5 Descriptors for environmental noise(s) . 8
5.1 Single events . 8
5.1.1 Descriptors . . . 8
5.1.2 Event duration . 8
5.2 Repetitive single events . 8
5.3 Continuous sound . 9
6 Noise annoyance . 9
6.1 Descriptors for community noise . 9
6.2 Frequency weightings . 9
6.3 Adjusted levels . 9
6.3.1 Adjusted sound exposure levels . 9
6.3.2 Adjusted equivalent continuous sound pressure level .10
6.4 Rating levels .10
6.4.1 One sound source .10
6.4.2 Combined sources .10
6.5 Composite whole-day rating levels .11
7 Noise limit requirements .11
7.1 General .11
7.2 Specifications.12
7.2.1 Noise descriptors.12
7.2.2 Relevant time intervals .12
7.2.3 Sound sources and their operating conditions .12
7.2.4 Locations . .12
7.2.5 Propagation conditions .13
7.2.6 Uncertainties .13
8 Reporting assessments of environmental noise(s) and estimation of long-term
community annoyance response .13
8.1 Estimation of long-term annoyance response of communities .13
8.2 Test report .13
Annex A (informative) Adjustments for sound source rating levels .15
Annex B (informative) High-energy impulse sounds .20
Annex C (informative) Sounds with strong low-frequency content .22
Annex D (informative) Relationships to estimate the percentage of a population highly
annoyed and the 95 % prediction interval as a function of adjusted day-evening-
night and day-night sound levels .24
Annex E (informative) Estimated prevalence of a population highly annoyed as a function
of adjusted day-evening-night or day-night sound levels using the community
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ISO 1996-1:2016(E)

tolerance level formulation .26
Annex F (informative) Estimated prevalence of a population highly annoyed as a function of
adjusted day-evening-night or day-night sound level using a regression formulation .33
Annex G (informative) Annoyance caused by exposure to sound in multi-source environments .39
Annex H (informative) Theory-based approach to predict the growth of annoyance.41
Bibliography .45
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ISO 1996-1:2016(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
This third edition cancels and replaces the second edition (ISO 1996-1:2003), which has been technically
revised. In particular, the following subclauses and annexes have been added or revised: 3.6, 6.3.1, 6.5,
8.1, 8.2.1 i), Annex A, Annex D, Annex E, Annex F, Annex G, and Annex H.
ISO 1996 consists of the following parts, under the general title Acoustics — Description, measurement
and assessment of environmental noise:
— Part 1: Basic quantities and assessment procedures
— Part 2: Determination of sound pressure levels
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ISO 1996-1:2016(E)

Introduction
To be of practical use, any method of description, measurement, and assessment of environmental noise
is intended to be related in some way to what is known about human response to noise. Many adverse
consequences of environmental noise increase with increasing noise, but the precise dose-response
relationships involved continue to be the subject of scientific debate. In addition, it is important that
all methods used be practicable within the social, economic, and political climate in which they are
used. For these reasons, there is a very large range of different methods in use around the world for
different types of noise, and this creates considerable difficulties for international comparison and
understanding.
The broad aim of the ISO 1996 series is to contribute to the international harmonization of methods of
description, measurement, and assessment of environmental noise from all sources.
The methods and procedures described in this part of ISO 1996 are intended to be applicable to noise
from various sources, individually or in combination, which contribute to the total exposure at a site.
At the stage of technology at the time of publication of this part of ISO 1996, the evaluation of long-
term noise annoyance seems to be best met by adopting the adjusted A-weighted equivalent continuous
sound pressure level, which is termed a “rating level”.
The aim of the ISO 1996 series is to provide authorities with material for the description and assessment
of noise in community environments. Based on the principles described in this part of ISO 1996, national
standards, regulations, and corresponding acceptable limits for noise can be developed.
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INTERNATIONAL STANDARD ISO 1996-1:2016(E)
Acoustics — Description, measurement and assessment of
environmental noise —
Part 1:
Basic quantities and assessment procedures
1 Scope
This part of ISO 1996 defines the basic quantities to be used for the description of noise in community
environments and describes basic assessment procedures. It also specifies methods to assess
environmental noise and gives guidance on predicting the potential annoyance response of a community
to long-term exposure from various types of environmental noises. The sound sources can be separate
or in various combinations. Application of the method to predict annoyance response is limited to areas
where people reside and to related long-term land uses.
Community response to noise can vary differently among sound sources that are observed to have
the same acoustic levels. This part of ISO 1996 describes adjustments for sounds that have different
characteristics. The term “rating level” is used to describe physical sound predictions or measurements
to which one or more adjustments have been added. On the basis of these rating levels, the long-term
community response can be estimated.
The sounds are assessed either singly or in combination, allowing for consideration, when deemed
necessary by responsible authorities, of the special characteristics of their impulsiveness, tonality,
and low-frequency content, and for the different characteristics of road-traffic noise, other forms of
transportation noise (such as aircraft noise), and industrial noise.
This part of ISO 1996 does not specify limits for environmental noise.
NOTE 1 In acoustics, several different physical measures describing sound can have their level expressed in
decibels (e.g. sound pressure, maximum sound pressure, and equivalent continuous sound pressure). The levels
corresponding to these physical measures normally will differ for the same sound. This often leads to confusion.
Therefore, it is necessary to specify the underlying physical quantity (e.g. sound pressure level, maximum sound
pressure level, and equivalent continuous sound pressure level).
NOTE 2 In this part of ISO 1996, quantities are expressed as levels in decibels. However, some countries
validly express the underlying physical quantity, such as maximum sound pressure, in pascal or sound exposure
in pascal-squared seconds.
NOTE 3 ISO 1996-2 deals with the determination of sound pressure levels.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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ISO 1996-1:2016(E)

3.1 Expression of levels
NOTE For levels defined in 3.1.1 to 3.1.6, it is essential that frequency weighting or frequency bandwidth, as
applicable, be specified, and time weighting, if applicable, be specified.
3.1.1
time-weighted and frequency-weighted sound pressure level
ten times the logarithm to the base 10 of the ratio of the time-mean-square of the sound pressure to
the square of a reference value, being obtained with a standard frequency weighting and standard time
weighting
Note 1 to entry: Sound pressure is expressed in pascal (Pa).
Note 2 to entry: The reference value is 20 μPa.
Note 3 to entry: Time-weighted and frequency-weighted sound pressure level is expressed in decibels (dB).
Note 4 to entry: The standard frequency weightings are A-weighting and C-weighting as specified in IEC 61672-1,
and the standard time weightings are F-weighting and S-weighting as specified in IEC 61672-1.
3.1.2
maximum time-weighted and frequency-weighted sound pressure level
greatest time-weighted and frequency-weighted sound pressure level within a stated time interval
Note 1 to entry: Maximum time-weighted and frequency-weighted sound pressure level is expressed in
decibels (dB).
3.1.3
N percentage exceedance level
time-weighted and frequency-weighted sound pressure level that is exceeded for N % of the time
interval considered
Note 1 to entry: N percentage exceedance level is expressed in decibels (dB).
EXAMPLE L is the A-frequency-weighted, F-time-weighted sound pressure level exceeded for
AF95,1h
95 % of 1 h.
3.1.4
peak sound pressure level
ten times the logarithm to the base 10 of the ratio of the square of the peak sound pressure to the
square of the reference value
Note 1 to entry: The reference value is 20 μPa.
Note 2 to entry: Peak sound pressure level is expressed in decibels (dB).
Note 3 to entry: Peak sound pressure should be determined with a detector as defined in IEC 61672-1. IEC 61672-
1 only specifies the accuracy of a detector using C-weighting.
Note 4 to entry: The peak sound pressure is the maximum absolute value of the instantaneous sound pressure
during a stated time interval.
3.1.5
sound exposure level
L
E
ten times the logarithm to the base 10 of the ratio of the sound exposure, E, being the integral of the
square of the sound pressure, p, over a stated time interval or event of duration, T (starting at t and
1
ending at t ), to a reference value, E
2 0
E
L =10lg dB
E
E
0
where
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ISO 1996-1:2016(E)

t
2
2
   Ep= ()ttd ;
∫
t
1
2
   E = 400 µPa s
0
Note 1 to entry: Sound exposure is expressed in pascal-squared seconds. Sound exposure level is expressed in
decibels (dB).
2
Note 2 to entry: Because of practical limitations of the measuring instruments, p is always understood to denote
the square of a frequency-weighted and frequency band-limited sound pressure. If a specific frequency weighting
as specified in IEC 61672-1 is applied, this should be indicated by appropriate subscripts; e.g. E , denotes the
A 1 h
A-weighted sound exposure over 1 h.
Note 3 to entry: The duration, T, of the integration is included implicitly in the time integral and need not to
be reported explicitly. For measurements of sound exposure over a specified time interval, the duration of
integration should be reported and the notation should be L .
E,T
Note 4 to entry: For sound exposure levels of an event, the nature of the event should be stated.
Note 5 to entry: When applied to a single event, the sound exposure level is called “single-event sound
exposure level”.
3.1.6
equivalent continuous sound pressure level
L
eq,T
ten times the logarithm to the base 10 of the ratio of the time-average of the square of the sound
pressure, p, during a stated time interval of duration, T (starting at t and ending t ), to the square of
1 2
the reference sound pressure, p
0
Note 1 to entry: The A-weighted equivalent continuous sound pressure level is
t
1 2
2
pt()dt
A
∫
T t
1
L =10lg dB
Aeq,T
2
p
0
where
p (t) is the A-weighted instantaneous sound pressure at running time t;
A
p is equal to 20 µPa.
0
Note 2 to entry: The equivalent continuous sound pressure level is also termed “time-averaged sound pressure
level”. It is expressed in decibels (dB).
3.2 Time intervals
3.2.1
reference time interval
time interval to which the rating of the sound is referred
Note 1 to entry: The reference time interval may be specified in national or international standards or by
local authorities to cover typical human activities and variations in the operation of sound sources. Reference
time intervals can be, for example, part of a day, the full day, or a full week. Some countries define even longer
reference time intervals.
Note 2 to entry: Different levels or sets of levels may be specified for different reference time intervals.
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ISO 1996-1:2016(E)

3.2.2
long-term time interval
specified time interval over which the sound of a series of reference time intervals is averaged or
assessed
Note 1 to entry: The long-term time interval is determined for the purpose of describing environmental noise as
it is generally designated by responsible authorities.
Note 2 to entry: For long-term assessments and land-use planning, long-term time intervals that represent some
significant fraction of a year should be used (e.g. 3 months, 6 months, and 1 year).
3.3 Ratings
3.3.1
adjustment
quantity, positive or negative, constant or variable, that is added to a predicted or measured acoustical
level to account for some sound character, the time of day, or the source type
3.3.2
rating level
predicted or measured acoustic level to which an adjustment has been added
Note 1 to entry: Measurements such as day/night sound pressure level or day/evening/night sound pressure
level are examples of rating levels because they are calculated from sound measured or predicted over different
reference time periods, and adjustments are added to the reference time interval equivalent continuous sound
pressure levels based on the time of day.
Note 2 to entry: A rating level may be created by adding adjustments to a measured or predicted level(s) to
account for some character of the sound such as tonality or impulsiveness.
Note 3 to entry: A rating level may be created by adding adjustments to a measured or predicted level(s) to account
for differences between source types. For example, using road traffic as the base sound source, adjustments may
be applied to the levels for aircraft or railway sources.
3.4 Sound designations
NOTE See Figure 1.
3.4.1
total sound
totally encompassing sound in a given situation at a given time, usually composed of sound from many
sources near and far
a) Three specific sounds A, B, and C under consideration, the residual sound and the total sound
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ISO 1996-1:2016(E)

b) Two specific sounds A and B under consideration, the residual sound and the total sound
Key
1 total sound
2 specific sound A
3 specific sound B
4 specific sound C
5 residual sound
NOTE 1 The lowest residual sound level is obtained when all specific sounds are suppressed.
NOTE 2 The dotted area indicates the residual sound when sounds A, B, and C are suppressed.
NOTE 3 In Figure 1 b), the residual sound includes the specific sound C as it is not under consideration.
Figure 1 — Total, specific, and residual sound designations
3.4.2
specific sound
component of the total sound that can be specifically identified and which is associated with a
specific source
3.4.3
residual sound
total sound remaining at a given position in a given situation when the specific sounds under
consideration are suppressed
3.4.4
initial sound
total sound present in an initial situation before any change to the existing situation occurs
3.4.5
fluctuating sound
continuous sound whose sound pressure level varies significantly, but not in an impulsive manner,
during the observation period
3.4.6
intermittent sound
sound that is present at the observer only during certain time periods that occur at regular or irregular
time intervals and is such that the duration of each such occurrence is more than about 5 s
EXAMPLE Motor vehicle noise under conditions of small traffic volume, train noise, aircraft noise, and air-
compressor noise.
3.4.7
sound emergence
increase in the total sound in a given situation that results from the introduction of some specific sound
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ISO 1996-1:2016(E)

3.4.8
impulsive sound
sound characterized by brief bursts of sound pressure
Note 1 to entry: The duration of a single impulsive sound is usually less than 1 s.
3.4.9
tonal sound
sound characterized by a single-frequency component or narrow-band components that emerge audibly
from the total sound
3.5 Impulsive sound sources
NOTE At the time of publication of this part of ISO 1996, no mathematical descriptor exists which can define
unequivocally the presence of impulsive sound or can separate impulsive sounds into the categories given in
3.5.1 to 3.5.3. These three categories, however, have been found to correlate best with community response.
Thus, the sources of sound listed in 3.5.1 to 3.5.3 are used to define impulsive sound sources.
3.5.1
high-energy impulsive sound source
explosive source where the equivalent mass of TNT exceeds 50 g, or sources with comparable
characteristics and degree of intrusiveness
Note 1 to entry: Sources of sonic booms include such items as aircraft, rockets, artillery projectiles, armour
projectiles, and other similar sources. This category does not include the short duration sonic booms generated
by small arms fire and other similar sources.
EXAMPLE Quarry and mining explosions, sonic booms, demolition, or industrial processes that use high
explosives, explosive industrial circuit breakers, and military ordnance (e.g. armour, artillery, mortar fire,
bombs, explosive ignition of rockets, and missiles).
3.5.2
highly impulsive sound source
source with highly impulsive characteristics and a high degree of intrusiveness
EXAMPLE Small arms fire, hammering on metal or wood, nail guns, drop-hammer, pile driver, drop forging,
punch presses, pneumatic hammering, pavement breaking, or metal impacts in rail-yard shunting operations.
3.5.3
regular impulsive sound source
impulsive sound source that is neither highly impulsive nor high-energy impulsive sound source
Note 1 to entry: This category includes sounds that are sometimes described as impulsive, but are not normally
judged to be as intrusive as highly impulsive sounds.
EXAMPLE Slamming of car door, outdoor ball games, such as football (soccer) or basketball, and church
bells. Very fast pass-bys of low-flying military aircraft can also fall into this category.
3.6 Day, evening, night sound levels
3.6.1
day sound level
L
day,h
equivalent continuous sound pressure level when the reference time interval is the day
Note 1 to entry: Subscript h indicates the number of hours, e.g. L .
day,12
Note 2 to entry: A day is normally the 12 h between 7 h and 19 h or the 15 h between 7 h and 22 h. However,
individual countries define day differently, e.g. 6 h to 18 h or 6 h to 22 h.
6 © ISO 2016 – All rights reserved

-
...

SLOVENSKI STANDARD
oSIST ISO 1996-1:2016
01-junij-2016
$NXVWLND2SLVPHUMHQMHLQRFHQDKUXSDYRNROMXGHO2VQRYQHYHOLþLQHLQ
RFHQMHYDOQLSRVWRSNL
Acoustics -- Description, measurement and assessment of environmental noise -- Part 1:
Basic quantities and assessment procedures
Acoustique -- Description, mesurage et évaluation du bruit de l'environnement -- Partie 1:
Grandeurs fondamentales et méthodes d'évaluation
Ta slovenski standard je istoveten z: ISO 1996-1:2016
ICS:
13.140 Vpliv hrupa na ljudi Noise with respect to human
beings
17.140.01 $NXVWLþQDPHUMHQMDLQ Acoustic measurements and
EODåHQMHKUXSDQDVSORãQR noise abatement in general
oSIST ISO 1996-1:2016 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST ISO 1996-1:2016

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oSIST ISO 1996-1:2016
INTERNATIONAL ISO
STANDARD 1996-1
Third edition
2016-03-01
Acoustics — Description,
measurement and assessment of
environmental noise —
Part 1:
Basic quantities and assessment
procedures
Acoustique — Description, mesurage et évaluation du bruit de
l’environnement —
Partie 1: Grandeurs fondamentales et méthodes d’évaluation
Reference number
ISO 1996-1:2016(E)
©
ISO 2016

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oSIST ISO 1996-1:2016
ISO 1996-1:2016(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

---------------------- Page: 4 ----------------------
oSIST ISO 1996-1:2016
ISO 1996-1:2016(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Expression of levels . 2
3.2 Time intervals . 3
3.3 Ratings . 4
3.4 Sound designations . 4
3.5 Impulsive sound sources . 6
3.6 Day, evening, night sound levels . 6
4 Symbols . 7
5 Descriptors for environmental noise(s) . 8
5.1 Single events . 8
5.1.1 Descriptors . . . 8
5.1.2 Event duration . 8
5.2 Repetitive single events . 8
5.3 Continuous sound . 9
6 Noise annoyance . 9
6.1 Descriptors for community noise . 9
6.2 Frequency weightings . 9
6.3 Adjusted levels . 9
6.3.1 Adjusted sound exposure levels . 9
6.3.2 Adjusted equivalent continuous sound pressure level .10
6.4 Rating levels .10
6.4.1 One sound source .10
6.4.2 Combined sources .10
6.5 Composite whole-day rating levels .11
7 Noise limit requirements .11
7.1 General .11
7.2 Specifications.12
7.2.1 Noise descriptors.12
7.2.2 Relevant time intervals .12
7.2.3 Sound sources and their operating conditions .12
7.2.4 Locations . .12
7.2.5 Propagation conditions .13
7.2.6 Uncertainties .13
8 Reporting assessments of environmental noise(s) and estimation of long-term
community annoyance response .13
8.1 Estimation of long-term annoyance response of communities .13
8.2 Test report .13
Annex A (informative) Adjustments for sound source rating levels .15
Annex B (informative) High-energy impulse sounds .20
Annex C (informative) Sounds with strong low-frequency content .22
Annex D (informative) Relationships to estimate the percentage of a population highly
annoyed and the 95 % prediction interval as a function of adjusted day-evening-
night and day-night sound levels .24
Annex E (informative) Estimated prevalence of a population highly annoyed as a function
of adjusted day-evening-night or day-night sound levels using the community
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oSIST ISO 1996-1:2016
ISO 1996-1:2016(E)

tolerance level formulation .26
Annex F (informative) Estimated prevalence of a population highly annoyed as a function of
adjusted day-evening-night or day-night sound level using a regression formulation .33
Annex G (informative) Annoyance caused by exposure to sound in multi-source environments .39
Annex H (informative) Theory-based approach to predict the growth of annoyance.41
Bibliography .45
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oSIST ISO 1996-1:2016
ISO 1996-1:2016(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.
This third edition cancels and replaces the second edition (ISO 1996-1:2003), which has been technically
revised. In particular, the following subclauses and annexes have been added or revised: 3.6, 6.3.1, 6.5,
8.1, 8.2.1 i), Annex A, Annex D, Annex E, Annex F, Annex G, and Annex H.
ISO 1996 consists of the following parts, under the general title Acoustics — Description, measurement
and assessment of environmental noise:
— Part 1: Basic quantities and assessment procedures
— Part 2: Determination of sound pressure levels
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oSIST ISO 1996-1:2016
ISO 1996-1:2016(E)

Introduction
To be of practical use, any method of description, measurement, and assessment of environmental noise
is intended to be related in some way to what is known about human response to noise. Many adverse
consequences of environmental noise increase with increasing noise, but the precise dose-response
relationships involved continue to be the subject of scientific debate. In addition, it is important that
all methods used be practicable within the social, economic, and political climate in which they are
used. For these reasons, there is a very large range of different methods in use around the world for
different types of noise, and this creates considerable difficulties for international comparison and
understanding.
The broad aim of the ISO 1996 series is to contribute to the international harmonization of methods of
description, measurement, and assessment of environmental noise from all sources.
The methods and procedures described in this part of ISO 1996 are intended to be applicable to noise
from various sources, individually or in combination, which contribute to the total exposure at a site.
At the stage of technology at the time of publication of this part of ISO 1996, the evaluation of long-
term noise annoyance seems to be best met by adopting the adjusted A-weighted equivalent continuous
sound pressure level, which is termed a “rating level”.
The aim of the ISO 1996 series is to provide authorities with material for the description and assessment
of noise in community environments. Based on the principles described in this part of ISO 1996, national
standards, regulations, and corresponding acceptable limits for noise can be developed.
vi © ISO 2016 – All rights reserved

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oSIST ISO 1996-1:2016
INTERNATIONAL STANDARD ISO 1996-1:2016(E)
Acoustics — Description, measurement and assessment of
environmental noise —
Part 1:
Basic quantities and assessment procedures
1 Scope
This part of ISO 1996 defines the basic quantities to be used for the description of noise in community
environments and describes basic assessment procedures. It also specifies methods to assess
environmental noise and gives guidance on predicting the potential annoyance response of a community
to long-term exposure from various types of environmental noises. The sound sources can be separate
or in various combinations. Application of the method to predict annoyance response is limited to areas
where people reside and to related long-term land uses.
Community response to noise can vary differently among sound sources that are observed to have
the same acoustic levels. This part of ISO 1996 describes adjustments for sounds that have different
characteristics. The term “rating level” is used to describe physical sound predictions or measurements
to which one or more adjustments have been added. On the basis of these rating levels, the long-term
community response can be estimated.
The sounds are assessed either singly or in combination, allowing for consideration, when deemed
necessary by responsible authorities, of the special characteristics of their impulsiveness, tonality,
and low-frequency content, and for the different characteristics of road-traffic noise, other forms of
transportation noise (such as aircraft noise), and industrial noise.
This part of ISO 1996 does not specify limits for environmental noise.
NOTE 1 In acoustics, several different physical measures describing sound can have their level expressed in
decibels (e.g. sound pressure, maximum sound pressure, and equivalent continuous sound pressure). The levels
corresponding to these physical measures normally will differ for the same sound. This often leads to confusion.
Therefore, it is necessary to specify the underlying physical quantity (e.g. sound pressure level, maximum sound
pressure level, and equivalent continuous sound pressure level).
NOTE 2 In this part of ISO 1996, quantities are expressed as levels in decibels. However, some countries
validly express the underlying physical quantity, such as maximum sound pressure, in pascal or sound exposure
in pascal-squared seconds.
NOTE 3 ISO 1996-2 deals with the determination of sound pressure levels.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
IEC 61672-1, Electroacoustics — Sound level meters — Part 1: Specifications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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3.1 Expression of levels
NOTE For levels defined in 3.1.1 to 3.1.6, it is essential that frequency weighting or frequency bandwidth, as
applicable, be specified, and time weighting, if applicable, be specified.
3.1.1
time-weighted and frequency-weighted sound pressure level
ten times the logarithm to the base 10 of the ratio of the time-mean-square of the sound pressure to
the square of a reference value, being obtained with a standard frequency weighting and standard time
weighting
Note 1 to entry: Sound pressure is expressed in pascal (Pa).
Note 2 to entry: The reference value is 20 μPa.
Note 3 to entry: Time-weighted and frequency-weighted sound pressure level is expressed in decibels (dB).
Note 4 to entry: The standard frequency weightings are A-weighting and C-weighting as specified in IEC 61672-1,
and the standard time weightings are F-weighting and S-weighting as specified in IEC 61672-1.
3.1.2
maximum time-weighted and frequency-weighted sound pressure level
greatest time-weighted and frequency-weighted sound pressure level within a stated time interval
Note 1 to entry: Maximum time-weighted and frequency-weighted sound pressure level is expressed in
decibels (dB).
3.1.3
N percentage exceedance level
time-weighted and frequency-weighted sound pressure level that is exceeded for N % of the time
interval considered
Note 1 to entry: N percentage exceedance level is expressed in decibels (dB).
EXAMPLE L is the A-frequency-weighted, F-time-weighted sound pressure level exceeded for
AF95,1h
95 % of 1 h.
3.1.4
peak sound pressure level
ten times the logarithm to the base 10 of the ratio of the square of the peak sound pressure to the
square of the reference value
Note 1 to entry: The reference value is 20 μPa.
Note 2 to entry: Peak sound pressure level is expressed in decibels (dB).
Note 3 to entry: Peak sound pressure should be determined with a detector as defined in IEC 61672-1. IEC 61672-
1 only specifies the accuracy of a detector using C-weighting.
Note 4 to entry: The peak sound pressure is the maximum absolute value of the instantaneous sound pressure
during a stated time interval.
3.1.5
sound exposure level
L
E
ten times the logarithm to the base 10 of the ratio of the sound exposure, E, being the integral of the
square of the sound pressure, p, over a stated time interval or event of duration, T (starting at t and
1
ending at t ), to a reference value, E
2 0
E
L =10lg dB
E
E
0
where
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t
2
2
   Ep= ()ttd ;
∫
t
1
2
   E = 400 µPa s
0
Note 1 to entry: Sound exposure is expressed in pascal-squared seconds. Sound exposure level is expressed in
decibels (dB).
2
Note 2 to entry: Because of practical limitations of the measuring instruments, p is always understood to denote
the square of a frequency-weighted and frequency band-limited sound pressure. If a specific frequency weighting
as specified in IEC 61672-1 is applied, this should be indicated by appropriate subscripts; e.g. E , denotes the
A 1 h
A-weighted sound exposure over 1 h.
Note 3 to entry: The duration, T, of the integration is included implicitly in the time integral and need not to
be reported explicitly. For measurements of sound exposure over a specified time interval, the duration of
integration should be reported and the notation should be L .
E,T
Note 4 to entry: For sound exposure levels of an event, the nature of the event should be stated.
Note 5 to entry: When applied to a single event, the sound exposure level is called “single-event sound
exposure level”.
3.1.6
equivalent continuous sound pressure level
L
eq,T
ten times the logarithm to the base 10 of the ratio of the time-average of the square of the sound
pressure, p, during a stated time interval of duration, T (starting at t and ending t ), to the square of
1 2
the reference sound pressure, p
0
Note 1 to entry: The A-weighted equivalent continuous sound pressure level is
t
1 2
2
pt()dt
A
∫
T t
1
L =10lg dB
Aeq,T
2
p
0
where
p (t) is the A-weighted instantaneous sound pressure at running time t;
A
p is equal to 20 µPa.
0
Note 2 to entry: The equivalent continuous sound pressure level is also termed “time-averaged sound pressure
level”. It is expressed in decibels (dB).
3.2 Time intervals
3.2.1
reference time interval
time interval to which the rating of the sound is referred
Note 1 to entry: The reference time interval may be specified in national or international standards or by
local authorities to cover typical human activities and variations in the operation of sound sources. Reference
time intervals can be, for example, part of a day, the full day, or a full week. Some countries define even longer
reference time intervals.
Note 2 to entry: Different levels or sets of levels may be specified for different reference time intervals.
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3.2.2
long-term time interval
specified time interval over which the sound of a series of reference time intervals is averaged or
assessed
Note 1 to entry: The long-term time interval is determined for the purpose of describing environmental noise as
it is generally designated by responsible authorities.
Note 2 to entry: For long-term assessments and land-use planning, long-term time intervals that represent some
significant fraction of a year should be used (e.g. 3 months, 6 months, and 1 year).
3.3 Ratings
3.3.1
adjustment
quantity, positive or negative, constant or variable, that is added to a predicted or measured acoustical
level to account for some sound character, the time of day, or the source type
3.3.2
rating level
predicted or measured acoustic level to which an adjustment has been added
Note 1 to entry: Measurements such as day/night sound pressure level or day/evening/night sound pressure
level are examples of rating levels because they are calculated from sound measured or predicted over different
reference time periods, and adjustments are added to the reference time interval equivalent continuous sound
pressure levels based on the time of day.
Note 2 to entry: A rating level may be created by adding adjustments to a measured or predicted level(s) to
account for some character of the sound such as tonality or impulsiveness.
Note 3 to entry: A rating level may be created by adding adjustments to a measured or predicted level(s) to account
for differences between source types. For example, using road traffic as the base sound source, adjustments may
be applied to the levels for aircraft or railway sources.
3.4 Sound designations
NOTE See Figure 1.
3.4.1
total sound
totally encompassing sound in a given situation at a given time, usually composed of sound from many
sources near and far
a) Three specific sounds A, B, and C under consideration, the residual sound and the total sound
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b) Two specific sounds A and B under consideration, the residual sound and the total sound
Key
1 total sound
2 specific sound A
3 specific sound B
4 specific sound C
5 residual sound
NOTE 1 The lowest residual sound level is obtained when all specific sounds are suppressed.
NOTE 2 The dotted area indicates the residual sound when sounds A, B, and C are suppressed.
NOTE 3 In Figure 1 b), the residual sound includes the specific sound C as it is not under consideration.
Figure 1 — Total, specific, and residual sound designations
3.4.2
specific sound
component of the total sound that can be specifically identified and which is associated with a
specific source
3.4.3
residual sound
total sound remaining at a given position in a given situation when the specific sounds under
consideration are suppressed
3.4.4
initial sound
total sound present in an initial situation before any change to the existing situation occurs
3.4.5
fluctuating sound
continuous sound whose sound pressure level varies significantly, but not in an impulsive manner,
during the observation period
3.4.6
intermittent sound
sound that is present at the observer only during certain time periods that occur at regular or irregular
time intervals and is such that the duration of each such occurrence is more than about 5 s
EXAMPLE Motor vehicle noise under conditions of small traffic volume, train noise, aircraft noise, and air-
compressor noise.
3.4.7
sound emergence
increase in the total sound in a given situation that results from the introduction of some specific sound
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3.4.8
impulsive sound
sound characterized by brief bursts of sound pressure
Note 1 to entry: The duration of a single impulsive sound is usually less than 1 s.
3.4.9
tonal sound
sound characterized by a single-frequency component or narrow-band components that emerge audibly
from the total sound
3.5 Impulsive sound sources
NOTE At the time of publication of this part of ISO 1996, no mathematical descriptor exists which can define
unequivocally the presence of impulsive sound or can separate impulsive sounds into the categories given in
3.5.1 to 3.5.3. These three categories, however, have been found to correlate best with community response.
Thus, the sources of sound listed in 3.5.1 to 3.5.3 are used to define impulsive sound sources.
3.5.1
high-energy impulsive sound source
explosive source where the equivalent mass of TNT exceeds 50 g, or sources with comparable
characteristics and degree of intrusiveness
Note 1 to entry: Sources of sonic booms include such items as aircraft, rockets, artillery projectiles, armour
projectiles, and other similar sources. This category does not include the short duration sonic booms generated
by small arms fire and other similar sources.
EXAMPLE Quarry and mining explosions, sonic booms, demolition, or industrial processes that use high
explosives, explosive industrial circuit breakers, and military ordnance (e.g. armour, artillery, mortar fire,
bombs, explosive ignition of rockets, and missiles).
3.5.2
highly impulsive sound source
source with highly impulsive characteris
...